单选题

In planer operations the workpiece is                      on the table which reciprocates in a horizontal plane providing a straight-line cutting and feed action.

单选题 They account about 98% by weight of all metals produced.

单选题 Within the elastic range, the limiting value of the stress             which the stress and strain are proportional, is called the limit of proportionality.

单选题 Single-point cutting tools are mounted on an overhead cross rail and along the supported columns.

单选题 Planers are               to shapers because both machines are primarily used to produce flat and angular surfaces.

单选题 A control system is a              of devices that regulate an operation by administering the flow of energy and other resources to and from that operation.

单选题 Taylor pioneered studies in “scientific management ”          which methods for production by both men and machines were studied.

单选题 There is not a great difference between “this” steel and “that” steel; all are very similar               mechanical properties.

单选题 Of the 50                  metallic elements, only a few are produced and used in large quantities in engineering practice.